Brendan Gleeson (born 29 March 1955) is an Irish actor and film director. He is the recipient of three IFTA Awards, two BIFA's, and a Primetime Emmy Award and has been nominated twice for a BAFTA Award, five times for a Golden Globe Award and once for an Academy Award. In 2020, he was listed at number 18 on The Irish Times list of Ireland's greatest film actors. He is the father of actors Domhnall Gleeson and Brian Gleeson.

He is best known for his performance as Alastor Moody in the Harry Potter films (2005–2010). He is also known for his supporting roles in films such as Braveheart (1995), Michael Collins (1996), 28 Days Later (2002), Gangs of New York (2002), Cold Mountain (2003), Troy (2004), Suffragette (2015), Paddington 2 (2017), The Ballad of Buster Scruggs (2018), and The Tragedy of Macbeth (2021). He is also known for his leading roles in films such as The General (1998), In Bruges (2008), The Guard (2011), Calvary (2014), Frankie (2019), and The Banshees of Inisherin (2022). He received a nomination for the Academy Award for Best Supporting Actor for the lattermost film.

He won an Primetime Emmy Award in 2009 for his portrayal of Winston Churchill in the television film Into the Storm. He also received a Golden Globe Award nomination for his performance as Donald Trump in the Showtime series The Comey Rule (2020). From 2017 to 2019 he starred in the crime series Mr. Mercedes. He received an Emmy Award nomination for Stephen Frears' Sundance TV series State of the Union (2022).